MALIGNANT HYPERTHERMIA:

MALIGNANT HYPERTHERMIA:
Expect the Unexpected

By Kris Ellis

Although rare, with as many as one in 5,000 or as few as one in 65,000 incidents involving administration of general anesthesia with triggering agents, malignant hyperthermia (MH) is a significant concern that must be taken seriously by ambulatory surgery centers (ASCs).¹

Patients susceptible to MH may develop an MH crisis (MHC) in response to exposure to commonly used anesthetics. In MHC, hypermetabolic symptoms such as tachycardia and a high fever are produced, and may lead to cardiac arrest, organ failure, and possibly death.

Although great strides have been made in terms of understanding MH and determining who may be susceptible, there is still much to be learned. However, ASCs can, and should, make every effort to establish potential patient risk. This can include questions during the pre-operative examination such as:

• Is there a family or personal history of MH and/or any known atypical response to anesthesia?
• Is there a family or personal history of a muscle or neuromuscular disorder (e.g., muscle weakness, serious muscle cramps, etc.)?
• Is there a personal history of unexplained and unanticipated high fever either during or within the first several hours following surgery?
• Have there been unexpected deaths or complications arising from anesthesia (including within a dental office) with any family members or blood relatives?²

“At the same time, it’s important to realize that for most patients who are susceptible to MHC, the majority of them have perfectly normal lives — there’s no illness, there’s no obvious muscle disease, and there’s no way to know except when they have this crisis,” says Charles B. Watson, MD, FCCM, chairman of the Department of Anesthesia, and deputy surgeon-in-chief at Bridgeport Hospital in the Yale- New Haven Health System. Watson is also chairman of the MH Hotline Quality Assurance Committee. “One can screen, but there’s no way to definitively say that it’s not a risk for someone, unless of course they’ve been tested and their muscle was negative.”

Such a test involves biopsy of skeletal muscle from the thigh. This test is usually only performed on those with a family history of MH or who have experienced a previous adverse reaction to anesthesia. Molecular genetic blood testing is a more recent development that may also be useful in detecting MH susceptibility.

Because of the rather mysterious nature of MH, ASCs must be prepared to deal with unexpected incidents. “It’s a matter of preparation,” Watson says. “Everyone agrees that asking questions is very helpful and should be done, but at the same time, we understand that no matter how many questions we ask, most people who are susceptible to MH will be unknown, particularly in the outpatient setting, where you’re dealing with people who are, by and large, a little healthier. This means that you have to expect that anybody, of any age, could have it.”

In order to establish and maintain a level of preparedness and awareness of MH, Watson recommends simulating an MH incident. “Just as you have fire drills sometimes, you should probably mount an organization-wide review of what you would do if this happened and who you would contact,” he explains. To this end, he points to educational materials supplied by the Malignant Hyperthermia Association of the United States (MHAUS). “The MHAUS-sponsored ASC workbook is a very useful device in helping people work out these roles and gives real-life role-playing situations and set-ups.”

Although there is variation in how ASCs might choose to prepare, the same things are essentially needed. “Every one of them should have some arrangement with a local institution so that they can emergently move a patient who is very sick to that institution because of MHC or any other acute medical condition,” Watson continues. “I think organizational readiness is a function of having the right protocols and manuals in place, and having periodic training exercises and refresher courses that get the staff together so they can think through the process. I would say that it’s quite similar to the suggestions of the airway management group for avoiding problems with the airway; that is, there are protocols and people review them periodically so they know what they’re doing.”

Patients who are known to be MH susceptible still may undergo surgery. In these cases, however, drugs that trigger MH must be avoided. These are:

• Sevoflurane
• Desflurane
• Isoflurane
• Halothane
• Enflurane
• Methoxyflurane
• Succinylcholine

ASCs must decide for themselves whether or not they should accept MH-susceptible patients. “I think the circumstances have to define this,” Watson says. “If a center is miles and miles away from the nearest back-up ICU, then it probably would be better to have the patient done in a center that’s immediately affiliated with or connected with some institution. If the patient has MH susceptibility but is clearly not going to have triggering agents, and is not undergoing a particularly stressful thing, and has a negative history of unusual muscle complaints or problems, then it’s probably a reasonable thing to take care of in an outpatient setting.”

During a procedure, vigilant patient monitoring can make all the difference in successfully dealing with MHC. “If the patient is having general anesthesia, the first signs that a hypermetabolic crisis is evolving are the signs of a rising heart rate and increased carbon dioxide production,” says Watson. “So, one of the most sensitive indicators is exhaled carbon dioxide analysis. A rise in temperature is a late finding in MHC. It certainly occurs and it certainly can be severe. The best example of how carbon dioxide monitoring helps I can give is that most people exhale a certain amount as part of normal breathing. If they’re asleep, they breathe less out through the monitor.

So if the patient is breathing spontaneously and has a rising respiratory rate and a rising exhaled carbon dioxide level, and it just continues to go up in an unexpected way without an obvious reason for it, then that’s a clue that somebody needs to pay attention. Something is dramatically increasing body metabolism that needs to be evaluated so it can be treated before you have cardiac arrhythmias, malignant temperature elevation, and the lethal complications of the MHC, among other emergency possibilities.”

Watson notes that it can be helpful to get arterial blood gases in this kind of situation. Blood pressure, heart rate, respiration, and carbon dioxide exhalation should all be monitored as well. “Carbon dioxide exhalation can be looked at even when people are just sedated, so it should be possible to get information fairly quickly,” he says. “The arterial blood gas is a test that can provide very valuable information and can be obtained by any ASC that is connected to or affiliated with a hospital. Also, many ASCs have their own equipment for this kind of testing.”

Dianne Daugherty, executive director of MHAUS, again points to the MHAUS MH procedure manual for ASCs as a valuable resource to learn more about MH and how your center can best prepare itself for an incident. “As ASCs may not have as many staff members available to deal with this kind of situation as a hospital might, we developed the ASC manual to describe an MH situation and attempted to cover those ASC staff members that we felt could be involved in this kind of scenario,” she says. “The idea is to use the manual and fit it to your particular situation.”

The manual consists of a three-ring binder which contains information on MH, how to recognize it, and how to treat it. There are also check-off lists that describe what various operating room (OR) team members should do in the case of MHC. Brochures describing the OR protocol for treating an MH incident are also included, as well as a video that can help ASCs improve their response time. “Everything is right there at your fingertips, to be used for an inservice or to onboard a new person,” Daugherty says. “To ensure that staff members have gone through this education process and are aware of it can be very helpful.”

Finally, MHAUS offers a toll-free number that can be extremely helpful for ASCs in need of immediate advice or information. “The MH hotline number can be used in an MH emergency, or as as a sounding board to outline a plan of action for an MH-susceptible patient, for example,” Daugherty explains. “Callers feel a comfort level after reviewing their treatment plan with an MH expert, which can be helpful. We have an MH OR protocol available which prominently displays the MH hotline number and is made to be posted in the operating area. If you think you’re seeing an MH incident, we suggest you call the hotline and follow the steps outlined on the protocol, which you have hopefully practiced using the MH procedure manual. It could save a patient’s life.”

SAMBA Sessions of Particular Interest to ASCs

FRIDAY, OCT. 21, 2005, NEW ORLEANS
8-9:30 a.m.

PANEL DISCUSSION: WHERE DO WE DRAW THE LINE ON OUTPATIENT SURGERY?
Raymond G. Borkowski, MD

Inguinal Hernia Repair in a Child with History of Laryngeal Papillomatosis
Lucinda L. Everett, MD

Arteriovenous Fistula in a Patient with Diabetes
Brian M. Parker, MD

Abdominoplasty in a Patient with Obesity and Obstructive Sleep Apnea
Michael T. Walsh, MD

10-11:30 a.m.

PANEL DISCUSSION: ADMINISTRATIVE ASPECTS OF RUNNING AN AMBULATORY SURGERY CENTER
Stephen A. Cohen, MD, PhD, MBA

Ambulatory OR of the Future
Julian M. Goldman, MD

Providing Services at Ambulatory Surgical Centers: Differences From the Inpatient World
Karin Bierstein, JD, MPH

Service Quality and Productivity in Ambulatory Surgery
Stephen A. Cohen, MD, PhD, MBA

3-4:30 p.m.

PANEL DISCUSSION: MALIGNANT HYPERTHERMIA IN OUTPATIENTS: CASES FROM THE MHAUS HOTLINE
Ronald S. Litman, DO, FAAP, Henry Rosenberg, MD, Joseph R. Tobin, MD, PhD, Richard F. Kaplan, MD

For more details, go to www.sambahq.com